How to get audio to play out of both speakers?

I've been working on a project all day and the audio was fine, but I recently opened it and the audio is only playing out of the right side of my computer, and the right side of headphones. What happened?

I'm seeing a lot of material on the forum and the web with using an effect(?)  to fill the right/left ear but it doesn't work and I'd rather not have to do that to listen out of headphones/computer at all.

Any help on getting the audio to play in both left & right?

My audio has both (L)(R) tracks on the music and voice portions so it's not the file but Premiere